Spiroketals are known in the art and are commercially useful as fragrance materials. The industrial processes for the production of these compounds generally start form sclareol and manool and yield mixtures of the oxygenated spiroketals of formula

For example, U.S. Pat. No. 3,144,465 discusses the synthesis of a mixture of the oxygenated spiroketals I and II (R═O) starting from manool, by the epoxidation with peracetic, perbenzonic, monoperphthalic, percamphoric or performic acid, followed by oxidation. A further process also described [E. Demole, Experientia, 20, 609 (1964)] the semi-industrial production of a mixture of the oxygenated spiroketals I and II (R═O) starting from manool, which combines the epoxidation by perbenzoic acid with the ozonolysis of the resulting epoxide, the products thus obtained being then treated with p-toluenesulphonic acid. These methods lead to mixtures of the spiroketals I and II (R═O) in yields not higher than 30% and have the disadvantage of using toxic and/or expensive reagents, as well as the added disadvantage of producing mixtures of compounds in which one of the components is odorless, thereby reducing the commercial value of the final product for the application in the industry of perfumery.
As discussed in U.S. Pat. Nos. 4,970,163 and 5,212,078; U.S. Pat. No. 4,798,799 discloses the utilization of a culture containing the microorganism Hyphozyma roseoniger ATCC 20624 capable of producing the diol having the structure:
in a recoverable quantity upon the transformation of compounds including the sclareol compound having the structure:
Table 4, Col. 12 of this patent discloses yields of 96% when carrying out the reaction:
under fermentation conditions using ATCC 20624.U.S. Pat. Nos. 4,970,163 and 5,212,078 disclose carrying out the reaction
via microbiological methods using the organism Bensingtonia ciliata, ATCC 20919 and carrying out the reaction
via microbiological methods using the organism Cryptococcus laurentii, ATCC 20920.
Since manool, manool ketone and larixol ketone are valuable intermediates in production of the important compounds in perfumery, such as amber ketal, there is an ongoing need for the methods of carrying out these reactions to be developed.